As methods effective for the prevention of tooth decay, there are several means known to date, such as (1) strengthening the acid resistance of teeth to render their constituents harder to elute in acid, which represents one of the direct causes of dental caries, and (2) facilitating the remineralization process on teeth to compensate for their eluted constituents at a higher rate.
Since fluoride acts to turn hydroxyapatite which is a major constituent of teeth into a fluoroapatite to render the constituent hard to elute in acids and is highly effective for facilitating the formation of hydroxyapatite to thereby facilitate the remineralization of teeth, it has become common at dental clinicals to coat teeth with a fluoride as treatment for preventing dental caries. In such cases, the most commonly used fluoride formulation is an acidulated phosphate fluoride solution (hereinafter referred to as APF).
However, the APF treatment takes a long time to complete the formation of calcium fluoride, because it includes a process which facilitates the double decomposition of teeth by the action of an acid and then exploits calcium contained there to produce calcium fluoride for fluoride uptake into the teeth. Specifically, for this method of treatment, it has been necessary that APF is first applied onto human teeth to be left as it is for 4 minutes, and further, the eating and/or drinking is forbidden for additional 30 minutes or longer. In this case, a person undergoing the care or treatment is required to exercise patience in keeping his or her mouth open for 4 minutes after APF application, and further, such a patient subjected to the treatment may feel rather burdensome because APF has a nasty taste due to its strongly acidic taste. Especially, for patients who are children, such a bad taste might be more burdensome.
On the other hand, as periodontal disease patients increase in number, dentin hyperesthesia caused by a stimulus occurring when eating and/or drinking something hot or cold and transferred directly to pulp nerves due to exposed dentin at dental roots has now become a problem to be seriously dealt with. To prevent or treat this dentin hyperesthesia, it is necessary to block the transmission of external stimulus by heat, acids, or etc. to pulp nerves by obturating dental canaliculi present in dentin.
While it has so far been done as preventive and curative treatment for dentin hyperesthesia to apply a 5% sodium fluoride varnish coating onto teeth, such application treatment is not free from problems yet, in that this method uses calcium contained in teeth and saliva to obturate the dental canaliculi and it takes time for calcium to turn to its fluoride and thus a longer time elapses before the dental canaliculi is effectively obturated, or in that the effect of the treatment has a low persistence after application (cf. the nonpatent literature 1.)
The patent literature 1 given below discloses a product for the remineralization of dental enamel, containing a first separate ingredient containing a water-soluble calcium salt, and a second separate ingredient containing a phosphate and at least one water-soluble fluoride salt that produces fluorine ions. However, the mineralization product disclosed in the patent literature 1 is taught to be “applied as a mixture prepared by mixing the first and second solutions together” (cf. the patent literature 1, page 19, lines 3 to 4).
In this regard, in a case where the first and the second liquids are first mixed together and then the resultant mixture is applied on to the teeth, there has been a problem that it is difficult to form calcium phosphates selectively on a tooth surface, because if the first solution containing a water-soluble calcium salt is mixed with the second solution comprising a phosphate and a water-soluble fluoride salt, such calcium phosphates (including partially fluorinated salts) are formed in the mixture during the course of mixing.    Patent literature 1: JP-A-2001-523217    Nonpatent literature 1: “Tooth Wear and Dentin Hyperesthesia” translated by Kenichi Kobayashi, et al., p. 357, Ishiyaku Publishers, Inc., 2003
The present invention provides an oral cavity composition containing a first composition (A) and a second composition (B) given below, said first composition (A) and said second composition (B) being discretely packed from each other so that said two compositions can be alternately used and then come to be mixed with each other at each tooth region when applied thereto:    (A) a first composition containing a fluoride ion supplying compound and an inorganic phosphoric acid or a salt thereof; and    (B) a second composition containing a calcium salt of organic acid, wherein an organic acid constituting said calcium salt of organic acid has a pKa value ranging from 3 to 11, or at least one pKa value ranging from 3 to 11 when said organic acid has plural pKa values.